Colors viewed in an image are dependent on the light that illuminates the subject of the image. Different illuminants will lead to differences in reflected light from the surfaces of the image subject matter. The human visual system approximately corrects these differences in reflected light so that perceived surface color is approximately constant. However, when images are captured on media and viewed under a light source different than the source in the image scene, these natural corrections do not take place. Accordingly, it may be preferable for recorded images to be color-balanced to a standard, reference light source in order to appear as they would to the natural eye. This balancing or color correction can be performed once the scene illuminant is identified.
Under known methods, illuminant estimation employs a fixed set of known illuminants, which are each characterized by the gamut of chromaticities that are possible under that illuminant. A chromaticity histogram may be computed for the image and compared with model histograms